Structural and decorative members made from polymeric materials are well known in the building industry. For example, many parts of windows, doors, railings, decking, siding, flooring, fencing, trim, and the like (which are nonlimiting examples of building components) are produced by extrusion of polymers such as polyvinyl chloride (PVC) or composites made of PVC and fillers such as wood fiber, other organic and inorganic fillers, binders, and/or reinforcing materials. Other thermoplastic polymers, such as polyethylene, polypropylene, and acrylonitrile butadiene styrene (ABS), along with a variety of thermoset polymers, have also been found useful. A more sustainable class of polymers with less of an environmental impact is the class known as biopolymers such as polyesters derived from renewable resources, of which polylactic acid (PLA) is an example. PLA can be produced by fermentation of corn or other renewable resources, and degrades to relatively harmless substances after its useful life when deposited in a landfill or other waste location. PLA may also be depolymerized into lactic acid and repolymerized after appropriate processing to allow more economically viable recycling into a wide variety of useful products, thereby reducing the disposal burden. PLA is thus recyclable as well as being renewable.
PLA's sensitivity to hydrolysis and high temperatures, and particularly its relatively low heat distortion temperature (HDT), has made PLA, alone, unsuitable for use in most building construction materials and other components that may be exposed to the elements. Also, like other polyesters, adhesion of other polymers or coatings to the surface of PLA may be difficult to achieve. Thus, mechanisms that improve these deficiencies of PLA are desirable.